The present teachings are predicated upon providing an improved disc brake system for use with vehicles. For example, the disc brake system may be used with almost any vehicle (e.g. car, truck, bus, train, airplane, or the like). Alternatively, the disc brake system may be integrated into assemblies used for manufacturing or other equipment that require a brake such as a lathe, winder for paper products or cloth, amusement park rides, wind turbines, the like, or a combination thereof. However, the present teachings are most suitable for use with a passenger vehicle (i.e. a car, truck, sports utility vehicle, or the like). Typical disc brake systems have either a floating caliper or a fixed caliper as discussed below.
Generally, a floating caliper braking system and a fixed caliper brake system include a rotor, a caliper body, a support bracket, and an inboard brake pad and an outboard brake pad located on opposing sides of the rotor. The caliper body further includes a bridge, one or more fingers, and one or more piston bores. The piston bore houses a piston. The piston bore has a bore axis that the piston moves along during a brake apply and a brake release. The piston bore may include a fluid inlet, a closed wall, a front opening, and a cylindrical side wall that has a seal groove located near the front opening. Typically, the fluid inlet is located in the closed wall of the piston bore so that when pressure is applied the fluid will flow into the piston bore. During a pressure apply the fluid will push the piston towards the front opening and into contact with a brake pad and then the brake pad into contact with a rotor. The caliper housing, upon the brake pad contacting the rotor, moves so that the one or more fingers contact the opposing brake pad and then move the opposing brake pad into contact with the opposing side of the rotor so that a braking force is created. A fixed brake system has two or more opposing pistons that move the brake pads simultaneously towards and into contact with a rotor causing a brake apply.
Typical, pistons used in a brake include one open end and one closed end. The open end faces the brake pad and the closed end is in contact with the brake fluid. When brake pressure is applied the fluid pressure increases and the fluid pushes on the closed end of the piston. The fluid moves the open end of the piston axially, with respect to a rotor, into contact with the brake pad so that the brake pad contacts the rotor and creates a braking force. The fluid pressure exerts both an axial force on the piston and a radial force on the piston. The axial forces on the piston move the piston into contact with the brake pad. During a brake apply when the one or more pistons are in contact with the brake pads and the brake pads are in contact with the rotor a frequency is generated by the brake pads and rotor interfaces which causes brake squeal. Examples of attempts to damp phase modes of pistons are disclosed in U.S. Pat. Nos. 5,484,041; 5,492,202; and 8,561,762; U.S. Provisional Patent Application No. 2009/0114490; and Japanese Patent Nos. JP2002/213506 and JP2009/036337 all of which are expressly incorporated by reference herein in their entirety for all purposes.
It would be attractive to have a piston where the mode of the piston is damped, shifted, tuned, changed, or a combination thereof. It would be attractive to have a piston reduces brake squeal, vibration, harshness, noise, or a combination thereof by creating mass damping and reducing vibration at a brake pad and rotor interface. What is needed is a piston that shifts a phase mode of a piston so that the brake pad and rotor interface do not produce noise in range between 2 kHz and 16 kHz. What is needed is an adhesive and insert that goes in a piston and shifts the mode of the piston.